function y = func_1_nonmod_analytical(q, zeta, m, CONSTS)

    k0 = CONSTS.k0;
    a  = CONSTS.a;
    c = CONSTS.c;
    Z0 = 4*pi/c;
      
    y = (-1i*Z0*k0^2*a/2)*besselmx(double('J'), m+1, k0*a*q, 0).^2 .* exp(-k0*q*abs(zeta));

end